Resource-constrained project scheduling under a net present value objective attracts growing interest. Because this is an NP-hard problem, it is unlikely that optimum solutions can be computed for large instances. Thus, heuristics have become a popular research field. Up to now, however, tight...

This contribution generalizes the work of Drexl and Haase about the so-called proportional lot sizing and scheduling problem which was published in 1995. While the early paper considers single-level cases only, the paper at hand describes multi-level problems. 1t provides mixed-integer programs...

Where standard MLP-solvers fail to compute optimum objective function values for certain MLP-model formulations, lower bounds may be used as a point of reference for evaluating heuristics. In this paper, we compute lower bounds for the multi-level proportional lot sizing and scheduling problem...

This contribution introduces a mixed-integer programming formulation for the multi-level, multi-machine proportional lot sizing and scheduling problem. It also presents a genetic algorithm to solve that problem. The efficiency of that algorithm is due to an encoding of solutions which uses a...

A flow line consists of a sequence of work places (or stations) through which one or more producta (or models) move one-way in order to be processed. Each model requires specific Operations which must be performed in a predefined Order. To be able to do so, the stations must be equipped with...

This paper presents a mixed-integer program for the dynamic lot sizing and scheduling problem in a multi-level, single-machine environment. It turns out that in contrast to single-level problems the integration of initial inventory is a crucial aspect if generality should not be lost. It is...

This paper deals with lot sizing and scheduling for a single-stage production System where setup costs and times are sequence dependent. A large bücket mixed integer programming (MIP) model is formulated which considers only efficient sequences. A tailor-made enumeration method of the...

Cellular automata were used to model and to simulate phenomena in the area of physics, biology and medicine. In this paper it is now shown how the idea of cellular automata can be applied to optimization problems as well. As an example a cellular automaton is used as a basis for solving...

This contribution presents two heuristic approaches for multi-level, single-machine lot sizing and scheduling. The first one is a variant of a so-called randomized regret based heuristic which is assumed to be the fastest available method for this particular class of problems. The second...